i he result* lend to show thai tfn 

 Ivu , mnhtlanO populations are mow 



similar to each other than to the 

 < ,I C ,i.,k- population. Also, the Glcn- 

 . population does nut appear to 

 h.ivc mote aHmiiics with one main- 

 | JIH I population than i he ulher. 



Onlv one juvenile animal was 

 „ uP |.eJ in December 19<-7. (Sec 

 I ,hle r.l Many were trapped in 

 L,nuiir\ I'^iS. hul only one new 

 (iiwnile was trapped in late Febru- 

 ,,,-v Mating must therefore lake place 

 Ifoin November to late December, 

 allowing a gestation period of 21 

 days and a weaning peiiod or lour 

 ueckv A more detailed study of the 

 reproductive condition uf the rat. by 

 M,. R. M. Wameke dining the 

 reiiod 27 September to 5 October 

 |4(,S indicated lhat the breeding 

 ve;-.son was about lo hegin 



hour animals which were mature 

 in January I'.** were still alive in 

 Decemhct 1968. It is not known if 

 „v animals live an> longer ihan two 

 v«rars. 



C()VI I I SIONS AMI DlSllSSION 



"I here YiiA recently been a revision 

 ol Rtintn species in Auslralia, based 

 on cross breeding! espenmeuts. Hor- 

 ner and Taylor. 196?) I he popula- 

 tion of rats in Portland was once 

 regarded as a separate species I torn 

 the Gippsland population, the former 

 heme called R guyi. and the latter 

 K. itidtf/ftt, These Iwo species, and 

 a Western Australian species called 

 filtitm have now been grouped 

 tajpfhW as the one Species /?. 

 , It is almost certain lhat the 

 popiilalion on Greater Glenni.. Maud 

 can he ascribed lo Ihe species K 

 hun/>r.». in vpnc of the tnorpho- 

 tu^ical differences heie dcsciibed 1" 

 A.-tild be unrealistic at this stage to 

 call Ihe Glenmc tal a new sub- 

 species, /\s seen in Tables 4 and 



febru«iry, \97\ 



5, there ate nut many morphological 

 differences between the Glcnnie. 

 Gippsland and Portland papulations. 

 Hie most sti iking dillcrence is the 

 large overall si/c ot the Glennic 

 population. Ibis is of interest a.s it 

 seems to be a common Feature of 

 island races of small mammals to be 

 of large size. (Corbet. 1963). The 

 Glcnnie population also has rela- 

 tively longer nasal bones, bul lew 

 olhcr significant differences esist 



The density of the population is 

 very much higher than is normally 

 found on the mainland. One source 

 (Warneke. unpublished I quotes a 

 figure of 4,8 individuals pet acre. 

 The high density on Glcnnie niav be 

 due lo all or any of a number of 

 laclor.s There is a general lack of 

 predators on the island. Natural pre- 

 dators on the mainland, bul absent 

 on Glcnnie, include snakes and many 

 species ol predatory birds. There are 

 some predatory birds from ihe main- 

 land feeding on Glcnnie, bul very 

 lew inhabit the island, due to u 

 shortage of suitable .testing sites, 

 Other predaiors absent on Glemtic 

 are feral cats, and foxes. The intro- 

 duction of these to the mainland 

 may have had considerable ellcci on 

 the small mammal fauna ol Aiisir.ih.i 



(.neater Glcnnie Wand does not 

 support a rabbit population Although 

 it is not suggested lhat direct com- 

 petition lakes place, rabbits haU- 

 seriously .dlccied the natural habitat 

 on other Bass Siiail islands. 



[i appears,, from the lirtlc informa- 

 tion on home range obtained, ihai 

 there is no appreciable dilfetencc- 

 Irorn lhat occurring in less dciine 



ropUlalitJIIS. 



I he skulK and skias which werv 

 collecled Imm the island in Decem- 

 ber )967, have been deposited in the 

 museum of the Department of Zoo- 

 louv and Comparative Phvsiologv. 

 Mnnash University. Melbourne. 



37 



